So if I took the A8 transmission out of my car and had a shop rebuild, to stock specifications, with no modifications other using new parts would it require any reprogramming to any of the modules in the car to function properly?

I was told after a stock rebuild programming is required.

 

No programming, just a relearn procedure.

 

So what is the relearn procedure and how is it accomplished?

 

Red as stated above , garage relearn procedure must be done anytime you work on an A8
The procedure 1st puts the transmission in learning mode and will cycle all shift servos to learn what preasure/volume is needed and what is the release time for each clutch pack . The trans has to be up to temp before the proceas will start and foot needs to be held firmly on the brake pedal ( and its imperiative u do not drive the car until it has been completed ) . The trans will make some pretty crazy noises during this part of the test but it's all normal

After completing the 1st part , the TCM is now in learning mode for about the next 100 to 200 miles, it is measuring the input shaft speed and output shaft speed during each gear change as it searches for the correct preasure to apply , and the correct release time for each clutch pack to make a perfect shift

It is very important during this time to vary your driving style , drive it like your fathers Buick at times but more importantly at times you need to drive it like you stole it and all points in between otherwise you might experence poor shift quality .

During this time you might experience poor shift quality , harsh down shifts , shift flair , this is all normal and part of the relearn process

Any competent transmission shop has diagnostic equipment ( GDS2 is one , plus you need a GM MDI comunications device ) that is needed and knows how to do this process , if they don't... RUN , do not walk away as I would not let them work on my car

Dave

 

Dcasole, thank you that's exactly what I was looking for..

So, it sounds like the relearn process is a procedure that is a accomplished by driving it in a prescribed manner ... OR is diagnostic equipment necessary for proper operation after a rebuild?

I'm asking because I'm looking to buy a Z06 that "may" need some transmission work. I was quoted $8,200 for a transmission rebuild at a reputable shop and was considering pulling the transmission out myself and having a shop complete the rebuild.

Many Thanks!!
Brian

 

Hi Brian , so the answer to your question is , both , you need the proper diagnosis tool to start the learning procedure , this is the garage part of the relearn where the TCM measures the preasure and the release times for each clutch pack and combination of clutch packs . I have GM"s GDS2 and a knock off GM MDI comunications device , there are others like an Autel or Snapon scanners that will do a TCM relearn but .... they are all expensive. Then the second part of the leaning procedure is the driving portion where the TCM monitors the input and output shaft speeds while you are driving as it fine tunes the shifts

As far as you removing the transmission, taking it somewhere to be rebuilt ,and then u reinstalling it , unless you really know what you are doing , between this relearn procedure, properly filling the transmission and then the most important step , upon install setting proper end play of the torque tube ( failure to do this step correctly will result in wiping out the engine thrust bearing in less than 200 miles) I would just let them do the whole job ...

Since the stock A8 reliably can hold up to modified 900 HP cars , I have to ask why does this car need a transmission rebuild ..... sounds like sombody who did not know what they were doing tried to "Tune" the TCM .... I would be real careful otherwise this could end up costing you a lot more than you are thinking .....

Dave

 

Dave, many thanks!! This is the information and advice I was looking for.

Brian

 

Also , I don't care how reputable the shop is , $8,200 for a rebuild is the " I don't want to do it price " ....

Heck you could buy a new trans for that price. And since they are pretty much indestructible, a used trans off of eBay is only $2,500 in most cases ....

Just food for thought
Dave

 

Dave,

I agree, I wanted to make sure I had all of the information necessary before I made a regrettable purchase. Sometimes a "good deal" turns out to be EXPENSIVE in the long run.

The particular car I'm looking at has a delayed and hard engagement in drive and reverse and this was after I test drove it. I understand this is one of two problems with the 2015 transmissions and that's why I'm thinking the transmission may need to come out for repairs.

Thanks again
Brian

 

@RED92LT1 Brian , If thats all you are worried about you don't need a rebuild, I am sure you have read my many posts about harsh engagement, 95% of the time a garage relearn will fix this problem . Have the owner get the garage relearn before you buy it .... I am confident that you will be surprised ...worst case , just let it run a minute before dropping it into drive or reverse

It takes a lot to destroy an A8 to the point of needed a rebuild , alot of us are making more than ZO6 power and beating on it pretty hard . All the bad stuff you hear about the A8 has to do with AFM and the lockup converter clutch engagement. GM blames it on fluid but it's really the way the TCM "Pulses" the lockup converter in V4 mode in order to filter out the harmonics of AFM operation .
The latest fluid is just a bandaide ..
Turn off AFM , put latest fluid and TCM program in it , and it will live forever

Dave

 

Well it's at a dealership so they should be able to do the "relearn procedure". The car has 72,000 miles on it and has been modified a bit so I really don't know the full story of the car, a chat with the previous owner would be helpful, not sure that's possible.

Many thanks for your advice and help!!
Brian